Gov. Rick Scott of Florida, who is expected to announce on Monday that he is running for the United States Senate against Bill Nelson, in Doral, Fla., last month.
Joe Raedle/Getty Images

CORAL SPRINGS, Fla. — By the time a town hall-style meeting on gun violence ended Tuesday night, the gathering of more than 1,400 people — bursting into repeated standing ovations and a loud chant of “Vote them out! Vote them out!” — had taken on the electric feeling of a political rally being held days before a big election.

Florida’s August primary is still more than four months away. The energized masses in Broward County, the most heavily Democratic county in the nation’s largest swing state, meant one thing for certain: trouble for Republicans, who have dominated Florida midterm elections for more a decade.

“We woke. This is a community that woke,” Drew Shimkus, 52, a single father and registered Democrat, said as he left the auditorium with his son, Bruce Elkins, 15, a high school freshman.

Democrats have reason for optimism, and not just because gun control has become a galvanizing issue in Florida politics after the Feb. 14 mass shooting at Marjory Stoneman Douglas High School in Parkland, an affluent Broward suburb that neighbors Coral Springs. Decision after decision by President Trump and his administration over the past year has forced Republicans campaigning across the divided state to either defend or break with the leader of their party.

The Republican Party’s best hope to help candidates navigate this treacherous new territory could come from an unlikely source: Gov. Rick Scott, who is expected to announce on Monday that he is running for the United States Senate against Bill Nelson, the Democratic incumbent.

Mr. Scott, a multimillionaire former health care executive whose style is more suited to the boardroom than the stump, is not frequently sought to campaign for fellow Republicans. But if the governor operates as he has in the past, he will likely spend big and early on television ads that could benefit other Republicans unable to purchase much airtime in Florida’s expensive broadcast markets. His campaign team, unencumbered by a serious primary challenge, will be able to focus on mobilizing voters for the November general election.

In Mr. Scott, Mr. Nelson will face his toughest opponent since his election to the Senate in 2000; Democrats are expected to invest tens of millions of dollars to defend his seat. But Mr. Scott, too, will have to answer for Mr. Trump. He led a “super PAC” raising money for the president during the 2016 election, and has been a frequent guest at the White House and Mar-a-Lago, the president’s Palm Beach estate.

In the past year, as he has prepared for the Senate race, Mr. Scott has broken with the president several times. He pressed the White House to let 32,500 Haitians, living in Florida under temporary protected status, remain in the country. He opposed the end of the Deferred Action for Childhood Arrivals program that has protected many immigrants brought into the country illegally as children from deportation. He pushed against allowing oil drilling off Florida’s shores. And he made repeated trips to Puerto Rico in the aftermath of Hurricane Maria, trying to establish a response to the catastrophic storm that was more proactive than the federal government’s.

Most important, perhaps, Mr. Scott signed off on new restrictions on firearm purchases after the Parkland shooting in defiance of the National Rifle Association, neutralizing some of the opposition he would have otherwise faced from vocal students and their families. That has not stopped Democrats from accusing the governor of acting only when it was politically convenient, especially given the lack of state action after a gunman killed 49 people at the Pulse nightclub in Orlando in 2016.

“On this issue, you know what, he pandered,” Mr. Shimkus said outside the meeting in Coral Springs. He said he plans to vote for Mr. Nelson.

A few steps away, a yelling match broke out between people leaving the event and five protesters holding signs in support of gun rights. “You’re indoctrinated!” one of the protesters shouted at a woman at the end of a fiery discussion. “You want to protect metal, I want to protect life!” a female high school student screamed at the protesters moments later.

As a statewide candidate, Mr. Scott will have some room to both embrace Mr. Trump on issues that are crucial to rural, conservative voters and reject him on matters important to urban liberals. That will be more difficult for Republicans running in congressional districts, especially in suburbs that have been trending lately in Democrats’ favor.

Senator Bill Nelson of Florida on Capitol Hill in March. In Mr. Scott, Mr. Nelson will face his toughest opponent since getting elected to the Senate in 2000.
Erin Schaff for The New York Times

Across the state, Republicans are trying to open narrow bits of daylight between themselves and the White House — and some have even shown a willingness to embrace moderate gun control measures. Representative Brian Mast of Palm City, on Florida’s Treasure Coast, has endorsed a ban on assault weapons, for example. Representative Carlos Curbelo of Miami helped introduce legislation that would raise the minimum age for purchasing any kind of firearm from 18 to 21.

On other issues, Mr. Curbelo has also warned that the tariffs Mr. Trump is imposing on steel are so broad that they might raise prices for residents of the Florida Keys who are trying to replace their metal roofs after Hurricane Irma. Representative Vern Buchanan of Sarasota has teamed up with Representative Debbie Wasserman Schultz, the former Democratic National Committee chairwoman, to work on a moratorium on offshore oil drilling around Florida.

“You’re going to see more and more campaigns — even more so than normal — localize and focus on the local issues that matter,” said Max Goodman, a spokesman for Mr. Buchanan.

Mr. Buchanan aired the first of an eight-week, $130,000 television ad campaign last week as an election-year precaution, Mr. Goodman said. The congressman’s son, James, unexpectedly lost a special election for a local, Republican-leaning state House district in February.

“It’s an offensive move, given this current climate,” Mr. Goodman said. “I don’t know if we’re nervous as much as we feel that we’re realists. It feels a little more like 2006 than 2010.”

In 2006, riding a wave of discontent over President George W. Bush and the unpopular war in Iraq, Florida Democrats picked up two congressional seats, helping their party take control of the House of Representatives. But they failed to win the governor’s mansion that year and lost two of three elected state cabinet positions. That has encouraged Republicans running for governor to keep the playbook that has worked for them even when the national political environment has favored Democrats.

Republicans have found midterm success in nominating candidates who appeal to the conservative base, said Brad Herold, a campaign adviser for Representative Ron DeSantis of Palm Coast, in northeast Florida, who is running for governor. “We’ve got the presidential endorsement. We’re not going to shy away from that,” Mr. Herold said, referring to a December post on Twitter by Mr. Trump backing Mr. DeSantis, before the congressman had even formally entered the race. Mr. Trump is expected to appear with Mr. DeSantis at a Florida event soon.

Mr. Trump’s declared support for Mr. DeSantis has not stopped the congressman’s Republican primary rivals from continuing to praise the president and his policies. Richard Corcoran, the speaker of the Florida House of Representatives and a still-undeclared candidate for governor, released an explosive commercial in January — on the same day Mr. DeSantis entered the race — opposing so-called sanctuary states, which Mr. Trump has railed against. Mr. Corcoran’s graphic ad showed a hooded man firing a gun at a young woman.

Adam Putnam, the state agriculture commissioner and the first major Republican to announce his candidacy for governor, grew up in his family’s citrus farming and cattle ranching business. He has touted Mr. Trump’s hard line on trade, even though it may result in retributive tariffs from China on Florida citrus and other crops.

“Nobody has ever gone to bat for Florida farmers and fought against illegal trade practices like President Trump,” Mr. Putnam said last week at a breakfast with Republican activists at a Cuban restaurant in Miami.

While Republicans hope to win their primaries by sticking close to Mr. Trump, Democrats appear split on how much to make their own campaigns for governor about the president. Philip Levine, the wealthy former mayor of Miami Beach, has already spent millions of dollars on television ads, though none of them are aimed specifically at Mr. Trump’s character.

“I don’t run against anybody,” Mr. Levine told a Jacksonville television station this week. “I run with my own message.”

His chief rival, Gwen Graham, a former congresswoman from Tallahassee, has taken the opposite approach. In her first digital ad, released this week, she mentions the president by name four times.